This invention relates to a driving gear for front and rear wheels of automobile, comprising an engine with a crank shaft disposed in the direction of width of the car body, a transmission supported on an engine case at one side axially of said crank shaft, a clutch provided between the engine and the transmission, a first differential gear coupled to the transmission, a second differential gear transmitting one output of the first differential gear to left and right wheels on the front or rear, a third differential gear transmitting the other output of the first differential gear to left and right wheels on the rear or front.